Shutter for sputtered particles in time-of-use indicator



June 15, 1965 A. v. BAZARIAN ETAL 3 5 SHUTTER FOR SPUTTERED PARTICLES IN TIMEOF- 'U SE INDICATOR med Feb. 19. 19 60 INVHVTORE ALBERT vr BAZARIAN KEITH W OLSON ATTORNEY United States Patent ration, a corporation of Delaware Filed Feb. 19, 1960, Ser. No. 9,860 3 Claims. (Cl. 313-146) The present invention relates to electron discharge devices and more particularly to electron discharge devices adapted to give an indication of time of use.

In many applications it is desirable to have an electronic device which can be easily connected into an operating circuit to indicate the total elapsed time of use of the circuit. It is desirable that such a device be small in physical size and require only a small amount of current for operation.

Of the various types of such devices which have been tried, collecting sputtered material from the cathode such as is illustrated and claimed in co-pending application Serial No. 741,900, filed June 13, 1958, now US. Patent No. 2,945,147, appears to be the most feasible. However, it has been found that the collector resistance does not change at the same rate during the initial hours of operation of the device for all units. In processing the device it is necessary to remove all impurities from the cathode. This causes deposits on the collector of other than pure cathode material, such as for example, a mix ture of the pure metal and various oxides of the metal plus other impurities. These deposits produce a widespread variation in the initial resistance vs. time characteristics of the devices.

The present invention provides novel means for preventing deposits on the collector during the processing of the device. A shutter is provided to shield the collector during the processing stage and is moved to permit normal operation of the device after the processing has been completed.

It is an object of the invention to provide an improved elapsed time of use indicator.

Another object of the invention is to provide an improved elapsed time of use indicator of small physical size and of a low power requirement.

Another object of the invention is to provide an improved elapsed time of use indicator having a uniform resistance vs. time characteristic.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment is illustrated by way of example.

In the drawing:

FIGURE 1 is a cutaway view of a device embodying the invention with the shielding means located for proc essmg.

FIGURE 2 is a cutaway view of the device of FIG- URE 1 with the shielding means changed for normal operation.

Referring now to the drawing, an electron discharge device is indicated generally by the numeral 5 and has an envelope 6 of glass or other suitable material. The envelope 6 includes a button stem section 7 and tubulation 8.

An anode 9 of nickel or other suitable material is supported between spacers 10 and 11 and connected by lead 12 to pin 13 which extends through the stem 7. The spacers 10 and 11 may be mica or other suitable material and are supported in a conventional manner. Also positioned between the spacers 10 and 11 and spaced from ice the anode 9 is a rod-like cathode 14- of molybdenum or other suitable material having good sputtering characteristics. The cathode 14 is connected by conductor 15 to pin 16 extending through the base '7.

A cylinder collector 17 of glass or other suitable insulating material is positioned between the spacers 10 and 11 and spaced from the cathode 14 on the side away from the anode 9. The cylinder 17 has metallized coatlugs 18 adjacent each end thereof. Connectors 19 and 20 connect the metallized coatings 18 to pins 21 and 22 respectively. The spacers 10 and 11 have openings 23 and 24 therein concentric with the tubulation 8 and adapted to receive a shutter 25. The shutter 25 extends through the spacers 10 and 11 and is positioned between the cathode and the cylinder 17. While the shutter 25 15 illustrated as a cylinder, it is understood that it could be of any other configuration in so long as it is large enough to shield the cylinder 17 from the cathode 14. A getter 26 may be provided and supported in a conventional manner above the spacer 10.

In processing the device it is exhausted in the con ventional manner and filled with a suitable gas, such as for example, a mixture of neon and argon. Then the tubulation 8 is tipped oil and sealed with sufiicient length to receive the shutter 25. The device is then processed to clean all impurities from the cathode. Substantially all of the impurities are collected on the shutter 25 which prevents them from reaching the cylinder 17. The device is then inverted so that the shutter 25 drops into the tubulation 8 and then tipped OE and sealed at the proper length just above the envelope.

It is understood that other means could be provided for removal of the shutter such as a magnet to rotate the shutter out of the cathode-collector path, a spring mounted shutter in which the spring could be released by burning with a high current, or an organic film which could be removed by heat.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made Without departing from the scope of the invention.

What is claimed is:

1. An elapsed time of use indicator comprising an envelope, an ionizable gas filling for said envelope, an anode, a cathode spaced from said anode, said cathode being of a material having a predetermined sputtering rate when bombarded with ionized gaseous particles, an insulated collector spaced from said cathode, upper and lower space-rs supporting said anode, cathode, and collector, and shielding means adapted for positioning by said spacers between said cathode and said collector when processing said device and movable from between said cathode and said collector after processing.

2. The combination as set forth in claim 1 in which said cathode material is molybdenum.

3. The combination as set forth in claim 1 in which said collector is a glass cylinder.

References Cited by the Examiner UNITED STATES PATENTS 1,917,854- 7/33 Rentschler 316-9 X 2,600,121 6/52 McGee et a1. 3169 X 2,667,600 1/54 Golf 316-9 X 2,945,147 7/60 Johnstone et al. 3l3217 DAVID J. GALVIN, Primary Examiner. RALPH G. NILSON, ARTHUR. GAUSS, Examiners. 

1. AN ELAPSED TIME OF USE INDICATOR COMPRISING AN ENVELOPE, AN IONIZABLE GAS FILLING FOR SAID ENVELOPE, AN ANODE; A CATHODE SPACED FROM SAID ANODE, SAID CATHODE BEING OF A MATERIAL HAVING A PREDETERMINED SPUTTERING RATE WHEN BOMBARDED WITH IONIZED GASEOUS PARTICLES, AN INSULATED COLLECTOR SPACED FROM SAID CATHODE, UPPER AND LOWER SPACERS SUPPORTING SAID ANODE, CATHODE, AND COLLECTOR, AND SHIELDING MEANS ADAPTED FOR POSITIONING BY SAID 